Given the relatively high speeds of many forms of transportation and their somewhat unpredictable operating conditions, retraint barriers are frequently employed to maintain the desired separation of passengers, cargo, and equipment in the event of an abrupt stop. This is particularly true of aircraft where emergency landings, at relatively high speeds, are sometimes required. Under these conditions, cargo and equipment may be thrown forward in the aircraft, presenting a substantial risk of injury or death to the crew in the cockpit. Further, important, expensive equipment located in the cockpit may be damaged or destroyed.
While it sometimes is possible to adequately restrain equipment and cargo by securing the individual pieces directly to the structure of the aircraft, a number of problems are presented. First, a particular piece of equipment, for example, may not be located adjacent a structural member of sufficient strength to withstand the load developed by the equipment under such conditions. Second, the equipment or cargo involved may not be readily susceptible to a form of direct attachment having suitable strength. Third, the nature and strength of the direct attachment required may make it difficult and time-consuming to load and unload cargo, as well as replace equipment. Finally, direct attachment of a large number of pieces of equipment and cargo may be expensive and consume an inordinate amount of space.
As an alternative to adequately and individually securing each item of cargo and equipment, some prior art proposals secure equipment and/or cargo to the aircraft by smaller, less substantial forms of direct attachment and utilize a barrier to provide the primary means of restraint.
One example of such a restraint barrier is illustrated in U.S. Pat. No. 2,669,402 (Del Mar). There, a high-strength network of radial and concentric yieldable bands is employed to reinforce an aircraft impact bulkhead. The bulkhead separates the crew and cargo and the network is located forward of the bulkhead. In the event that sudden deceleration of the aircraft causes the individual cargo restraints to fail, the cargo is initially restrained by the impact bulkhead. The force exerted by the cargo may distend the bulkhead and network, applying a preload to the network. If the force is sufficient to cause the impact bulkhead to fail, the network immediately assumes the full restraint of the cargo, thereby protecting the crew.
An alternative form of restraint for use on vehicles having open, flat cargo-carrying surfaces is disclosed in U.S. Pat. No. 3,779,174 (Doyle et al.). A retaining panel is employed as a bulkhead and is adjustable on the cargo surface of the vehicle by way of a comb arrangement that engages stake pockets provided along the cargo surface. The retaining panel consists of wooden boards, or sheet metal, held in place by metal channels provided around the perimeter of the panel. With the position of the panel adjusted as desired, the panel is chained to the cargo-carrying surface.
While such barriers may be capable of restraining cargo and equipment in the event of an abrupt deceleration of the vehicle, they suffer from a number of shortcomings. For example, in order to withstand high loads, such barriers must be relatively heavy and consume a significant amount of vehicle space. This appears particularly true of the arrangement disclosed by Doyle et al. where wood or sheet metal is used to withstand the loads applied. Similarly, the arrangement disclosed by Del Mar requires the use of an impact bulkhead in conjunction with the high-strength network of bands.
Prior art restraint devices also are not particularly adaptable to preexisting vehicle structure and conditions. For example, the impact bulkhead and cable network employed by Del Mar extend across the entire cross section of the fuselage. Thus, movement of the crew between the cockpit and cargo area is limited. In addition, it may be difficult to add such an arrangement to an existing aircraft at a particular location, given the structural requirements of the impact bulkhead. The Doyle et al. arrangement appears equally unadaptable to existing vehicles in that stake pockets must be provided along the cargo-carrying surface of the vehicle. A final shortcoming of the prior art restraint barriers is their relative cost. The complexity of the arrangements makes their production and installation in the vehicle expensive. The weight and space requirements of such barriers also make operation of the vehicle so equipped less economical by increasing fuel consumption and decreasing cargo space.
In light of the shortcomings of the prior art, a restraint barrier is needed that is capable of withstanding substantial loading, and which is lightweight, adaptable to existing vehicle structure, and economical to construct, install, and use.